Quantum stochastic trajectories for particles and fields based on positive P-representation

TL;DR

This paper introduces a positive P-representation-based phase-space method for modeling bosonic fields interacting with quantum emitters, enabling stochastic trajectory simulations of open quantum systems with particle conservation.

Contribution

It develops a broad, Hamiltonian-independent formalism using stochastic trajectories to describe light-matter interactions and quantum emitters, incorporating particle conservation and multi-level systems.

Findings

Formulates stochastic equations of motion for combined emitter-field systems.

Provides a general framework applicable to diverse quantum systems.

Lays groundwork for future studies on collective spontaneous emission.

Abstract

In this work we introduce a phase-space description based on the positive P representation for bosonic fields interacting with a system of quantum emitters. The formalism is applicable to collective light-matter interactions and open quantum systems with decoherence. Conservation of particle numbers is considered, and a Jordan-Schwinger transformation enables the representation of multi-level quantum emitters. The evolution of the phase-space description of the combined system of emitters and field is formulated in terms of stochastic trajectories and we derive the rules of mapping from traditional quantum mechanics to this stochastic formalism. The resulting equations of motion encode deterministic, classical evolution with quantum effects incorporated by stochastic noise terms. The framework's equations and properties are provided without specifying the Hamiltonian, aiming for broad applicability in diverse research domains. A potential future application is the quantum mechanical description of collective spontaneous emission of an incoherently pumped ensemble of atoms.